(edit: on re-reading OP, not sure where you fall in this situation - are they making a copyright claim against you? Or, are you looking to sue them?)

Best bet is to get a lawyer buddy to send a C&D (gratis or case of beer or whatever) and hope it just goes away. Otherwise, prepare for a long arduous expensive journey.

I've been involved with a couple of similar cases at my company. One is currently pending, another was decided in our favor, but the company went belly-up, so the only thing we have to show for our "win," is some court papers and a bunch of lawyer's invoices. Note that these were not solely copyright claims, but facets of larger lawsuits.

Here are some questions that we've been faced with:

1) Can you clearly demonstrate that their FAQ is newer than yours?
2) Can you demonstrate that they visited your site?
3) Can you demonstrate that they have been adjudicated against for similar theft of content?
4) Can you present any other sites that they may have filched content from?
5) If you've made updates to your content, can you demonstrate that they have made similar updates in due course?
6) Slightly easier, you'll have to prove that they are a competing business.
7) You'll have to prove that their use of your material is for commercial gain and also not protected under fair use.
8) You'll want to demonstrate that you've lost potential business, and be able to attribute that loss to their use of your content.
9) Can you demonstrate that your content is unique, and not attributable to yet another site?
10) Can you demonstrate that you have taken action in any other circumstances where somebody stole your content?

There are loads of other questions that will come up, but these are a good foundation.

I am getting a lawyer but mostly to negotiate a settlement. It is their FAQ, they think mine is a copy of it. I use the same questions but answer them in my own way. I thought for a FAQ on the same service asking common questions I would be ok.

I am getting a lawyer but mostly to negotiate a settlement. It is their FAQ, they think mine is a copy of it. I use the same questions but answer them in my own way. I thought for a FAQ on the same service asking common questions I would be ok.